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CRW(1)			FreeBSD	General	Commands Manual			CRW(1)

     crw -- Process RAW	Canon PowerShot	photos

     crw [-c] [-s num] [-g num]	[-b num] [-r num] [-l num] [-B num] [-L	num]
	 [-bw] [-inside] [-2] [-3] [-4]	files

     The crw utility processes RAW output files	(.crw) from Canon Powershot
     digital cameras, typically	converting them	into .ppm files.  By default,
     crw uses a	gamma of 0.8 (the lower	the brighter) and a low-light compen-
     sation value of 16	(higher	values == more compensation, 0 disables).
     Different CCDs also have different	scaling	factors	for their filter com-
     ponents.  This program will automatically scale filter components for the
     CCD (though our values may	not be entirely	correct.  The red scaling for
     the CanonG2 was wrong in the original program, before I fixed it).	 The
     program renormalizes the data to a	scaling	of 1.0/1.0/1.0 before applying
     adjustments specified on the command line.

     The resolution of the output file will typically be somewhat smaller then
     the resolution of the raw .crw file due to	edge effects during process-
     ing.  RAW files contain one color per pixel in a matrix which must	be
     processed to synthesize the missing colors	and generate photo output.
     You can see the raw CCD matrix (with thermal noise	and filter compensa-
     tion by default) by running the program with the option: -s -1.

     The following options are available:

     -c	   Generate the	converted image	file on	the standard output.  If not
	   specified the image file is generated using the input filename with
	   an appropriately replaced extension.

     -s	num
	   Specify the smoothness factor.  Currently only -1 and 0 may be
	   specified.  -1 will cause crw to transfer the raw CCD pixels	to the
	   standard output in the requested image file format.	The default is
	   0.  You can produce a certain degree	of smoothing by	changing the
	   low-light adjustment, which is the

     -L	   option.

     -g	num
	   Set the gamma.  The default is 0.8.	A value	of 1.0 will produce
	   output with no gamma	correction.  Lower values will produce
	   brighter output images.  Gamma is a non-uniform exponential adjust-
	   ment	of the image brightness	that tends to bring out	darker areas
	   of an image.	 This only works for .ppm image	output.

     -b	num
	   Set the brightness.	Brightness is a	more uniform, linear brighten-
	   ing of the image.  The default is 1.0.  A higher value will produce
	   a brighter image.  We recommend using the gamma adjustment whenever
	   possible instead of the brightness adjustment.

     -r	num
	   Set the red scaling.	 The default is	1.0.  The red and blue scaling
	   factors are typically used to compensate for	artificial lighting.

     -l	num
	   Set the blue	scaling.  The default is 1.0.  The red and blue	scal-
	   ing factors are typically used to compensate	for artificial light-

     -B	num
	   This	option may be used to set the thermal noise compensation.  The
	   only	valid values are 0 or 1.  The default is 1, enabling compensa-
	   tion.  Setting this option to zero disables thermal noise compensa-
	   tion.  Thermal noise	produces a baseline value for the CCD pixels.
	   The actual CCD data contains	a 'black border' area on all four
	   sides which the processing program uses to determine	the baseline.
	   The baseline	is then	subtracted from	the data.  It is not typically
	   useful to disable noise compensation.

     -L	num
	   Set the lowlight compensation factor.  The default is 16.  A	value
	   of 0	will disable lowlight compensation.  Lowlight compensation
	   changes the bleedover in the	weighted compensation algorithm	used
	   to generate the missing colors in the output	photo.	The higher the
	   value, the more of an 'averaging' effect we get (the	weighting be-
	   comes less important).  The result is a softening of	the edge en-
	   hancement processing	and more blending of adjacent pixels, reducing
	   the apparent	noise in the output image when you view	it.  Lowlight
	   compensation	does not seem to adversely effect normal photos	so the
	   default is set fairly high.

     -bw   Black-and-white output.  This only works for	.ppm image output.
	   The magnitude is calculated and stored into all three color guns to
	   produce a black and white picture.


	   Set the red scale to	0.7 to compensate for indoor lighting (same as
	   using -r 0.7).  If not specified we assume outdoor lighting (par
	   1.0 for red and blue	scale options).

     -2	   Generate a 24-bit PPM file (default)

     -3	   Generate a 48-bit PSD (Adobe	Photoshop) file

     -4	   Generate a 48-bit PNG

	   Specify one or more files to	process.  Unless -c is specified crw
	   will	generate an output file	named after the	input file with	an ap-
	   propriate extension change.


     The crw utility was created by Dave Coffin	in 1997.  Matt Dillon reworked
     the main interpolation algorithm extensively in this port and is cur-
     rently maintaining	it for FreeBSD.

4th Berkeley Distribution	 June 16, 2002	     4th Berkeley Distribution


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